In a wireless communications system, there is typically a fixed amount of air link resources available for communications. As more and more individuals start to utilize wireless services and as service providers continue to offer new and varied wireless services, the demand and competition for those limited resources continues to increase. Therefore, there is a need for new and inventive methods and apparatus to boost system capacity. In a wireless cellular communications system, interference between adjacent cells and/or sectors becomes an important consideration where bandwidth is reused in adjacent cells and/or adjacent sectors. Therefore it would be beneficial if new methods and apparatus for cellular systems used to boost system capacity also tended to address and/or minimize inter-sector and/or inter-cell interference.
It has been well understood that the use of multiple antennas in multiple-input multiple-output (MIMO) systems can increase the spectral efficiency for wireless communications. Theoretically, the capacity boost from applying multiple antennas at the base station and/or the mobile stations can be potentially a factor which is equal to the number of antennas used in the system. However, practically there are problems associated with such a system using multiple antennas. For instance, in reality such a gain in system capacity is not always attainable due to a limited scattering environment and other practical restrictions in the system. Furthermore, system complexity increases significantly in order to realize the MIMO gain. For example, for an Uplink (UL)/Downlink (DL) Space division multiple access (SDMA) scheme, more scheduling bits have to be assigned per schedule since more than one user will be assigned to the same time/frequency slab. Also, sophisticated interference cancellation schemes, e.g., a Minimum Mean Square Error (MMSE) receiver based scheme, have to be applied to the base station and/or the mobile stations since the spatial signatures of the two users on the slab will be correlated more or less. With two antennas, a traditional MIMO scheme using spatial arrays (2×2) can increase the capacity, but to a limited degree.
In view of the above discussion, it would be desirable if improved methods and apparatus could be developed to provide improved performance gain in terms of increase in system capacity, better signal to noise ratio, increased spectral efficiency over the network, and/or reduced inter cell interference. It would be advantageous if such improved methods and apparatus were able to achieve some of these goals without significantly increasing the system complexity as compared to a single antenna system.